CN214094026U

CN214094026U - Recondensing system

Info

Publication number: CN214094026U
Application number: CN202022538584.1U
Authority: CN
Inventors: 贾保印; 宋媛玲; 刘以荣; 王红; 赵甲递; 周怡诺
Original assignee: China National Petroleum Corp; China Huanqiu Contracting and Engineering Corp
Current assignee: China National Petroleum Corp; China Huanqiu Contracting and Engineering Corp
Priority date: 2020-11-05
Filing date: 2020-11-05
Publication date: 2021-08-31
Anticipated expiration: 2030-11-05

Abstract

The disclosure provides a recondensing system, and belongs to the technical field of natural gas storage. The recondensing system comprises a main output pipe, wherein a first pressure sensor is arranged on the main output pipe; the bottom end of the recondenser is communicated with the main output pipe; the device comprises an evaporation gas input pipe, a first temperature sensor and a standard volume flow detection device are arranged on the evaporation gas input pipe; the LNG storage tank is characterized in that the LNG input pipe is provided with a second temperature sensor, a first flow sensor and a flow regulating valve, and the LNG input pipe is also provided with a density detection device for measuring the density of LNG in the LNG storage tank so as to reflect the components of the LNG. Therefore, the controller can adjust the flow of the LNG injected into the recondenser through the flow adjusting valve based on the temperature and the standard volume flow of the BOG and the temperature and the flow of the LNG, so that the cold energy input into the recondenser by the LNG can be matched with the heat brought into the recondenser by the BOG, and the recondensing effect is improved.

Description

Recondensing system

Technical Field

The present disclosure relates to the field of natural gas storage technologies, and in particular, to a recondensing system.

Background

Natural gas is a high-quality, high-efficiency and clean low-carbon energy, can form a good complementation with other low-emission energy sources such as nuclear energy, renewable energy sources and the like, and is the most practical choice for clean energy supply. Currently, due to the emphasis on environmental protection, the increasing demand for energy, and the diversification of energy resources, the energy consumption of LNG (Liquefied Natural Gas) steadily increases year by year in our country, the application range is continuously expanded, the market potential is huge, and the construction of LNG receiving stations will be in the gold development period.

In the actual production and operation process of the LNG receiving station, due to factors such as leakage of environmental heat, volume replacement in the process of loading or unloading a ship, work of a low-pressure delivery pump and the like, a certain amount of BOG can be generated in a Gas phase space of an LNG storage tank and a BOG (Boil Off Gas) pipeline, the main component of the BOG is methane which is combustible explosive Gas, and the direct discharge not only can pollute air and form a greenhouse effect, but also can cause accidents such as explosion, fire and the like.

Generally, the BOG is processed by the LNG receiving station in a recondensing process, in which the BOG is compressed to a low pressure (generally 0.5MPaG to 1.0MPaG) by a BOG compressor, and then mixed with LNG pumped out by an LNG low-pressure pump in a packing layer of a recondenser, and the BOG is condensed into a liquid state by using the cold energy of the LNG, and then pressurized by a high-pressure pump and then delivered to a vaporizer. It is difficult to accurately control the flow of BOG and LNG to the recondensor, resulting in poor recondensation.

SUMMERY OF THE UTILITY MODEL

The disclosed embodiment provides a recondensing system, which can conveniently control the flow of BOG and LNG entering a recondenser, and improve the recondensing effect. The technical scheme is as follows:

embodiments of the present disclosure provide a recondensing system comprising:

the two ends of the main output pipe are respectively used for connecting the low-pressure pump and the high-pressure pump, and a first pressure sensor for detecting the pressure of the liquefied natural gas in the main output pipe is arranged on the main output pipe;

a recondenser, a bottom end of the recondenser being in communication with the main output pipe;

the evaporative gas input pipe is communicated with the top end of the recondenser, and is provided with a first temperature sensor for detecting the temperature of the evaporative gas in the evaporative gas input pipe and a standard volume flow detection device for determining the standard volume flow of the evaporative gas in the evaporative gas input pipe;

a natural gas input tube in communication with a top end of the recondenser;

the system comprises a main output pipe, a liquefied natural gas input pipe, a second temperature sensor, a first flow sensor and a flow regulating valve, wherein one end of the liquefied natural gas input pipe is communicated with the main output pipe, the other end of the liquefied natural gas input pipe is connected with a spray head, the spray head is positioned in the recondenser, and the liquefied natural gas input pipe is provided with the second temperature sensor for detecting the temperature of liquefied natural gas inside the second temperature sensor, the first flow sensor for detecting the flow of the liquefied natural gas inside the second temperature sensor, the flow regulating valve for regulating the flow of the liquefied natural gas inside the first flow sensor and the flow regulating valve;

a density detection device for measuring the density of the liquefied natural gas in the liquefied natural gas storage tank;

and the controller is used for adjusting the opening degree of the flow regulating valve and is connected with the first pressure sensor, the first temperature sensor, the standard volume flow detection device, the second temperature sensor, the flow regulating valve and the density detection device.

Optionally, the standard volumetric flow rate detection device includes a second pressure sensor, a second flow rate sensor, a third temperature sensor and a standard volumetric flow rate calculator, the second pressure sensor, the second flow rate sensor and the third temperature sensor are all disposed on the evaporation gas input pipe and are all connected to the standard volumetric flow rate calculator, and the standard volumetric flow rate calculator is connected to the controller.

Optionally, a first control valve is further disposed on the lng input pipe, and along a flow direction of the lng in the lng input pipe, the second temperature sensor, the first flow sensor, and the flow regulating valve are all located between the first control valve and the shower head.

Optionally, a liquid level regulating valve is arranged on the natural gas input pipe.

Optionally, a level gauge is included, the level gauge being located on an outer wall of the recondenser.

Optionally, an input device for manually inputting the density of the liquefied natural gas in the liquefied natural gas storage tank is further included, and the input device is connected with the controller.

Optionally, a fourth temperature sensor is disposed on the total output pipe.

Optionally, a second control valve is disposed on the main output pipe, the second control valve is located at one end of the main output pipe close to the low-pressure pump in the flow direction of the liquefied natural gas in the main output pipe, and a connection point of a recondenser and the main output pipe is located between the second control valve and the first pressure sensor.

Optionally, an exhaust tube is included, one end of the exhaust tube communicating with a top end of the recondenser.

Optionally, an exhaust valve is arranged on the exhaust pipe.

The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure at least comprise:

the temperature of BOG is detected by arranging the first temperature sensor on the evaporation gas input pipe, the standard volume flow of the BOG is detected by the standard volume flow detection device, the temperature of LNG is detected by the second temperature sensor on the liquefied natural gas input pipe, the flow of the LNG is detected by the first flow sensor, the flow of the LNG is adjusted by the flow adjusting valve, and the density of the LNG in the liquefied natural gas storage tank is measured by the density detection device to reflect the components of the LNG. Therefore, the controller can adjust the flow of the LNG injected into the recondenser through the flow adjusting valve based on the temperature and the standard volume flow of the BOG and the temperature and the flow of the LNG, so that the cold energy input into the recondenser by the LNG can be matched with the heat brought into the recondenser by the BOG, and the recondensing effect is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a schematic diagram of a recondensing system according to an embodiment of the disclosure.

Detailed Description

To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," "third," and similar terms in the description and claims of the present disclosure are not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the element or item listed before "comprises" or "comprising" covers the element or item listed after "comprising" or "comprises" and its equivalents, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, which may also change accordingly when the absolute position of the object being described changes.

Fig. 1 is a schematic diagram of a recondensing system according to an embodiment of the disclosure. As shown in fig. 1, the recondensing system includes: a main output pipe 10, a recondenser 20, a boil-off gas input pipe 30, a natural gas input pipe 40, a liquefied natural gas input pipe 50, a density detection device 60, and a controller 70.

Two ends of the main output pipe 10 are respectively used for connecting a low-pressure pump and a high-pressure pump, and a first pressure sensor 11 for detecting the pressure of the liquefied natural gas inside the main output pipe 10 is arranged on the main output pipe.

The bottom end of the recondenser 20 communicates with the main output pipe 10.

The boil-off gas input pipe 30 is communicated with the top end of the recondenser 20, and the boil-off gas input pipe 30 is provided with a first temperature sensor 31 for detecting the temperature of the boil-off gas inside thereof and a standard volume flow rate detection device 32 for determining the standard volume flow rate of the boil-off gas inside thereof.

A natural gas input tube 40 communicates with the top end of the recondenser 20.

One end of the liquefied natural gas input pipe 50 is communicated with the main output pipe 10, the other end of the liquefied natural gas input pipe 50 is connected with a spray head 51, the spray head 51 is positioned in the recondenser 20, and the liquefied natural gas input pipe 50 is provided with a second temperature sensor 52 for detecting the temperature of liquefied natural gas inside, a first flow sensor 53 for detecting the flow of liquefied natural gas inside, and a flow regulating valve 54 for regulating the flow of liquefied natural gas inside.

The density detection device 60 is used to measure the density of the liquefied natural gas in the liquefied natural gas storage tank.

The controller 70 is used to adjust the opening degree of the flow regulating valve 54, and the controller 70 is connected to the first pressure sensor 11, the first temperature sensor 31, the standard volumetric flow rate detecting device 32, the second temperature sensor 52, the flow regulating valve 54, and the density detecting device 60.

Illustratively, the Controller 70 may be a Programmable Logic Controller (PLC).

As shown in fig. 1, the first flow sensor 53 may be connected to a valve controller 541 of the flow regulating valve 54, and the valve controller 541 may be connected to the controller 70.

Optionally, the recondensing system may further include an input device for manually inputting the density of the liquefied natural gas in the liquefied natural gas storage tank, the input device being coupled to the controller 70. When the BOG is re-condensed, the density of the LNG in the LNG tank can be measured by the density detection device 60, and the data is supplied to the controller 70.

The input device may be, for example, a keyboard.

As shown in fig. 1, the reference volumetric flow rate detecting device 32 includes a second pressure sensor 321, a second flow rate sensor 322, a third temperature sensor 323, and a reference volumetric flow rate calculator 324, wherein the second pressure sensor 321, the second flow rate sensor 322, and the third temperature sensor 323 are all disposed on the evaporation gas input pipe 30, and are all connected to the reference volumetric flow rate calculator 324, and the reference volumetric flow rate calculator 324 is connected to the controller 70.

The second pressure sensor 321 is for detecting the pressure of the BOG in the boil-off gas feed pipe 30, the second flow sensor 322 is for detecting the flow rate of the BOG in the boil-off gas feed pipe 30, and the third temperature sensor 323 is for detecting the temperature of the BOG in the boil-off gas feed pipe 30. The second pressure sensor 321, the second flow sensor 322, and the third temperature sensor 323 supply the detected corresponding data to the standard volume flow calculator 324, and the standard volume flow calculator 324 calculates the standard volume flow of the BOG from the pressure, the flow rate, and the temperature of the BOG in the boil-off gas feed pipe 30.

As shown in fig. 1, the lng input pipe 50 is further provided with a first control valve 55, and the second temperature sensor 52, the first flow sensor 53 and the flow control valve 54 are located between the first control valve 55 and the shower head 51 along the flow direction of the lng in the lng input pipe 50.

With the first control valve 55 closed, the LNG inlet line 50 is shut off and LNG cannot enter the recondenser 20, and the first control valve 55 remains normally open when recondensation is required. The flow rate of LNG in the LNG input pipe 50 can be adjusted by changing the opening degree of the flow control valve 54, and the flow rate of LNG supplied to the recondenser 20 can be adjusted by changing the opening degree of the flow control valve 54 after the first control valve 55 is opened.

As shown in fig. 1, the total output pipe 10 is provided with a second control valve 13. In the flow direction of the lng in the main output pipe 10, the second control valve 13 is located at an end of the main output pipe 10 close to the low-pressure pump, and the connection of the recondenser 20 to the main output pipe 10 is located between the second control valve 13 and the first pressure sensor 11.

LNG is fed from a low-pressure pump 101 to one end of the main delivery pipe 10, and after passing through the main delivery pipe 10, enters a high-pressure pump 102 from the other end of the main delivery pipe 10. The second control valve 13 on the total output pipe 10 can control the on-off of the total output pipe 10. The second control valve 13 is kept open during recondensing of the BOG.

As shown in fig. 1, a fourth temperature sensor 12 is further disposed on the total output pipe 10. A fourth temperature sensor 12 is arranged at the end of the main output pipe 10 close to the high-pressure pump 102.

After entering the total output pipe 10, LNG is partially transported further along the total output pipe 10, and partially enters the LNG input pipe 50, enters the recondenser 20 to liquefy BOG, and then is collected from the bottom of the recondenser 20 into the total output pipe 10 to be transported further. The LNG merging from the recondenser 20 causes the LNG temperature in the main output pipe 10 to increase, and the temperature of the mixed LNG can be detected by the fourth temperature sensor 12, so that the recondensing system can be adjusted to make the LNG entering the high-pressure pump 102 within the required range of the process.

As shown in fig. 1, two total flow rate adjusting valves 14 are further disposed on the total output pipe 10, and a total flow rate controller 93 is connected to the two total flow rate adjusting valves 14 and the first pressure sensor 11 to adjust the opening degrees of the two total flow rate adjusting valves 14 to adjust the pressure in the total output pipe 10. One of the total flow control valves 14 may also be connected in series with a total flow sensor 15.

The bottom of the recondenser 20 may communicate with the main output pipe 10 through an on-off valve 22.

The recondensing system further comprises a saturation pressure calculator 91 and a differential pressure calculator 92, the saturation pressure calculator 91 being connected to the fourth temperature sensor 12 to derive a saturated vapor pressure at the temperature based on the temperature of the LNG detected by the fourth temperature sensor 12. The pressure difference calculator 92 is connected to the total flow rate controller 93 and the saturation pressure calculator 91 to calculate a difference between the saturated vapor pressure and the pressure in the total output pipe 10. The differential pressure calculator 92 may be coupled to the BOG compressor controller 94 to facilitate the BOG compressor controller 94 in adjusting the operating conditions of the BOG compressor. The BOG compressor is a BOG compressor that feeds BOG to the boil-off gas input pipe 30.

As shown in fig. 1, a third control valve 41 is disposed on the natural gas input pipe 40, and the on/off of the third control valve 41 can control the on/off of the natural gas input pipe 40.

The natural gas input pipe 40 is also provided with a liquid level regulating valve 42. The level control valve 42 is used to regulate the flow of NG (Natural Gas) in the Natural Gas inlet line 40 to maintain the liquid level in the recondenser 20.

In the flow direction of NG in the natural gas input line 40, a level regulating valve 42 may be located between the third control valve 41 and the recondenser 20.

As shown in fig. 1, the recondensing system also includes a level gauge 21, the level gauge 21 being located on the outer wall of the recondenser 20.

The level of liquid in the recondenser 20 is detected by the level gauge 21 to avoid excessive high or low liquid level in the recondenser 20 to ensure proper operation of the recondensing system.

The controller 421 of the level adjustment valve 42 may be connected to the level gauge 21 to control the opening of the level adjustment valve 42 to adjust the flow of NG based on the height of the liquid level in the recondenser 20.

As shown in fig. 1, the recondensing system also includes an exhaust tube 80, one end of the exhaust tube 80 communicating with the top end of the recondenser 20.

The vent 80 may vent the natural gas not liquefied in the recondenser 20. The other end of the vent line 80 may be routed to the BOG manifold and then returned to the boil-off gas input 30, again through the boil-off gas input 30 to the recondenser 20, or the other end of the vent line 80 may be connected to a flare to burn the vented natural gas.

As shown in fig. 1, the exhaust pipe 80 may be provided with an exhaust valve 81 to control the flow rate of the natural gas discharged in the exhaust pipe 80.

The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.

Claims

1. A recondensing system, comprising:

a main output pipe (10) with two ends respectively used for connecting the low-pressure pump and the high-pressure pump, wherein a first pressure sensor (11) used for detecting the pressure of liquefied natural gas in the main output pipe (10) is arranged;

a recondenser (20), the bottom end of said recondenser (20) being in communication with said total output pipe (10);

the evaporative gas input pipe (30) is communicated with the top end of the recondenser (20), and a first temperature sensor (31) for detecting the temperature of the evaporative gas in the evaporative gas input pipe (30) and a standard volume flow detection device (32) for determining the standard volume flow of the evaporative gas in the evaporative gas input pipe are arranged on the evaporative gas input pipe;

a natural gas input tube (40) in communication with a top end of the recondenser (20);

the liquefied natural gas automatic control system comprises a liquefied natural gas input pipe (50), wherein one end of the liquefied natural gas input pipe (50) is communicated with the main output pipe (10), the other end of the liquefied natural gas input pipe (50) is connected with a spray head (51), the spray head (51) is positioned in the recondenser (20), and the liquefied natural gas input pipe (50) is provided with a second temperature sensor (52) for detecting the temperature of liquefied natural gas inside the liquefied natural gas input pipe, a first flow sensor (53) for detecting the flow of the liquefied natural gas inside the liquefied natural gas input pipe, and a flow regulating valve (54) for regulating the flow of the liquefied natural gas inside the liquefied natural gas input pipe;

a density detection device (60) for measuring the density of the liquefied natural gas in the liquefied natural gas storage tank;

a controller (70) for adjusting the opening of the flow regulating valve (54), the controller (70) being connected to the first pressure sensor (11), the first temperature sensor (31), the standard volumetric flow detection device (32), the second temperature sensor (52), the flow regulating valve (54) and the density detection device (60).

2. The recondensing system of claim 1, wherein the standard volumetric flow sensing device (32) comprises a second pressure sensor (321), a second flow sensor (322), a third temperature sensor (323), and a standard volumetric flow calculator (324), the second pressure sensor (321), the second flow sensor (322), and the third temperature sensor (323) are all disposed on the boil-off gas input tube (30) and are all connected to the standard volumetric flow calculator (324), and the standard volumetric flow calculator (324) is connected to the controller (70).

3. The recondensing system of claim 1, wherein the lng input line (50) further comprises a first control valve (55), and the second temperature sensor (52), the first flow sensor (53), and the flow control valve (54) are located between the first control valve (55) and the showerhead (51) in a flow direction of the lng in the lng input line (50).

4. The recondensing system of claim 1, wherein a level regulating valve (42) is disposed on the natural gas input line (40).

5. The recondensing system of any of claims 1 to 4, further comprising a level gauge (21), the level gauge (21) being located on an outer wall of the recondenser (20).

6. A recondensing system according to any of claims 1 to 4, further comprising an input device for manually inputting the density of the LNG in the LNG storage tank, the input device being connected to the controller (70).

7. A recondensing system according to any of claims 1 to 4, wherein a fourth temperature sensor (12) is provided on the total output tube (10).

8. A recondensing system according to any of claims 1 to 4, wherein the main output line (10) is provided with a second control valve (13), the second control valve (13) being located at an end of the main output line (10) close to the low pressure pump in the flow direction of the liquefied natural gas in the main output line (10), and the connection of the recondenser (20) to the main output line (10) being located between the second control valve (13) and the first pressure sensor (11).

9. The recondensing system of any of claims 1 to 4, further comprising an exhaust tube (80), wherein one end of the exhaust tube (80) is in communication with a top end of the recondenser (20).

10. A recondensing system according to claim 9, wherein the exhaust tube (80) is provided with an exhaust valve (81).